This invention relates generally to an improved ultraviolet-absorbing amino compound, and in particular to an ultraviolet-absorbing amino compound which has superior outdoor durability over a long period of time, does not suffer from degradation in chemical resistance and moisture resistance even when used in large quantities and which is compatible over a wide range; to a paint containing said compound; and to a coated article having on its surface a coated film containing said compound.
Frequently, thermosetting synthetic resin paints are coated on the surfaces of articles, for example, automobiles and building materials, which are used outdoors for long periods of time. Ultraviolet light tends to degrade the coated films resulting in various defects in the films, such as cracks, peeling or gloss reduction. In addition, the ultraviolet light which passes through the upper region of the coating causes degradation for example, chalking of the intermediate regions of the coating or the surface layer of a primer coating beneath it, and consequently, the top coating tends to peel off.
Satisfactory ultraviolet absorbers which would avoid such defects in long-term outdoor use have been desired in the past, but sufficient results have not yet been obtained. Ultraviolet absorbers for paints are used in admixture with other ingredients, such as synthetic resins. The conventional ultraviolet absorbers, in long-term outdoor use, tend to volatilize or wash away and gradually lose their effects. Moreover, during the step of baking (curing) a coated film, conventional ultraviolet absorbers tend to volatilize. Thus, the amount of the ultraviolet absorber remaining in the hardened coated film is less than the amount actually mixed with the paint. This lowers the absorbing properties and results in much waste.
Attempts to prevent photodegradation by increasing the amount of the ultraviolet absorber to be mixed tend to result in deterioration of physical properties. Typically chemical resistance and moisture resistance of a coated film deteriorate, resulting in discoloration or blistering of the coating. In addition, conventional ultraviolet absorbers have poor compatibility with certain synthetic resins or solvents. Hence, they are not uniformly dispersed and tend to precipitate in the paints. This interferes with formation of a smooth coated surface.
Accordingly, it would be desirable to provide an improved ultraviolet-absorbing material which is free from these defects of conventional ultraviolet absorbers, has superior outdoor durability over a long period of time, does not suffer from degradation in chemical resistance and moisture resistance even when used in large quantities, and which has a wide range of compatability; a paint containing the material and a coated article having on its surface a coated film containing the material.